Characterization and identification of the candidate gene of rice thermo-sensitive genic male sterile gene <Emphasis Type="Italic">tms5</Emphasis> by mapping

Previous research has demonstrated that the thermo-sensitive genic male-sterile (TGMS) gene in rice was regulated by temperature. TGMS rice is important to hybrid rice production because the application of the TGMS system in two-line breeding is cost-effective, simple, efficient and overcomes the limitations of the cytoplasmic male sterility (CMS) system. AnnongS is the first discovered and deeply studied TGMS rice line in China. Previous studies have suggested that AnnongS-1 and Y58S, two derivative TGMS lines of AnnongS, were both controlled by a single recessive gene named tms5, which was genetically mapped on chromosome 2. In the current study, three populations (AnnongS-1 × Nanjing11, Y58S × Q611, and Y58S × Guanghui122) were developed to investigate the tms5 gene molecular map. Analysis of recombination events of sterile samples, utilizing 125 probes covering the tms5 region, suggested that the tms5 gene was physically mapped to a 19 kb DNA fragment between two markers, 4039-1 and 4039-2, located on the BAC clone AP004039. Following the construction of a physical map between the two markers, ONAC023, a member of the NAC (NAM-ATAF-CUC-related) gene family, was identified as the candidate of the tms5 gene.     

Recognition of an unnatural difluorophenyl nucleotide by uracil DNA glycosylase

The DNA repair enzyme uracil DNA glycosylase (UDG) utilizes base flipping to recognize and remove unwanted uracil bases from the genome but does not react with its structural congener, thymine, which differs by a single methyl group. Two factors that determine whether an enzyme flips a base from the duplex are its shape and hydrogen bonding properties. To probe the role of these factors in uracil recognition by UDG, we have synthesized a DNA duplex that contains a single difluorophenyl (F) nucleotide analogue that is an excellent isostere of uracil but possesses no hydrogen bond donor or acceptor groups. By using binding affinity measurements, solution (19)F NMR, and solid state (31)P[(19)F] rotational-echo double-resonance (REDOR) NMR measurements, we establish that UDG partially unstacks F from the duplex. However, due to the lack of hydrogen bonding groups that are required to support an open-to-closed conformational transition in UDG, F cannot stably dock in the UDG active site. We propose that F attains a metastable unstacked state that mimics a previously detected intermediate on the uracil-flipping pathway and suggest structural models of the metastable state that are consistent with the REDOR NMR measurements.     

Physiological responses to drought and shade in two contrasting Picea asperata populations

The responses of photosynthetic gas exchange, chlorophyll fluorescence, activities of antioxidant enzymes and lipid membrane peroxidation of two contrasting Picea asperata Mast. populations to 30% of full sunlight (shade) and full sunlight (sun) were investigated under well-watered and drought conditions. Two contrasting populations were from the wet and dry climate regions in China, respectively. For both populations tested, drought resulted in lower needle relative water content (RWC), CO₂ assimilation rate ( A ), stomatal conductance ( gs ) and effective PSII quantum yield ( Y ), and higher non-photochemical quenching ( qN ), superoxide dismutase (SOD), ascorbate peroxidase (APX) activities as well as malondialdehyde (MDA) levels and electrolyte leakage in sun plants, whereas these changes were not significant in shade plants. For the wet climate population, shade plants showed higher chlorophyll contents (Chl a , Chl b and Chl a + b ) than sun plants under both well-watered and drought conditions. Our study results implied that shade, applied together with drought, ameliorated the detrimental effects of drought. On the other hand, compared with the wet climate population, the dry climate population was more tolerant to drought in the sun treatment, as indicated by less decreases in A and mass-based leaf nitrogen content ( N _mass), more responsive stomata, greater capacity for non-radiative dissipation of excitation energy as heat (analysed by qN ), and higher level of antioxidant enzyme activities as well as lower MDA content and electrolyte leakage. These results demonstrated that the different physiological strategies were employed by the P. asperata populations from contrasting climate regions when the plants were exposed to drought and shade.     

Psychedelic-inspired drug discovery using an engineered biosensor

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湖南藤本植物胸径与其支柱木胸径的相关性

采用野外样株调查方法和11种数学方程与计算机软件SPSS13.0相结合的统计分析方法,对湖南藤本植物胸径大小与其支柱木的胸径大小之间的相关性进行了研究,其结果是:(1)全部藤本植物胸径大小与其支柱木胸径大小的比率是1:6.36,而缠绕、卷曲、搭靠和吸固各攀援方式的胸径大小与其支柱木的胸径大小的比率分别为1:5.61、1:4.92、1:5.89、1:15.46;其中吸固类藤本的支柱木胸径的平均值是最大的。(2)全部藤本植物胸径大小(y)与其支柱木胸径大小(x)的相关曲线是:y=-4.75×10-1 3.44×10-1x-1.13×10-2x2 1.61×10-4x3;缠绕类藤本植物胸径大小与其支柱木胸径大小的相关曲线是:y=2.68×10-1x0.829;卷曲类藤本植物胸径大小与其支柱木胸径大小的相关曲线有两条,分别是:y1=1.88×10-1x01.981,y2=e(1.93-12.222/x2);搭靠类藤本植物胸径大小与其支柱木胸径大小的相关曲线是:y=6.92-8.74×10-1x 4.95×10-2x2-7.45×10-4x3;吸固类藤本植物胸径大小与其支柱木胸径大小的相关曲线是:y=-1.16 3.64×10-1x-1.72×10-2x2 2.56×10-4x3。     

植物叶缘和叶脉发育调控的研究进展

通常可通过植物叶片的形态来区分不同植物的种类。叶片由茎顶端分生组织侧翼发育而成,为多种多样大小和形状的扁平结构。叶片的结构看似简单,但调控叶片形态和结构发育的分子机理错综复杂,叶片的发育受植物激素、转录因子、一系列蛋白因子及环境的共同调控。本文回顾了叶片边缘形态和叶脉发育研究的最新进展。在叶边缘形态方面,Aux/IAA生长素响应抑制家族蛋白通过调节生长素浓度最大点的离散分布影响小叶的起始和生长以及叶边缘结构;NAM/CUC转录因子促进叶边缘锯齿的分离以及复叶中小叶的分离和分化,NAM/CUC和Aux/IAA通过不同通路实现对生长素的调控;拟南芥RAX1基因/番茄Potato-leaf基因和拟南芥JAG基因/番茄LYR基因促进叶边缘锯齿发育;RCO调控复叶小叶的发育不通过改变生长素的分布来实现;在番茄中反式小干扰RNA途径中的因子参与叶边缘形态发育;另外,在拟南芥中,mir164A、CUC2、PIN1、DPA4、SVR9-1及SVR9L-1构成复杂的调控网络影响叶边缘锯齿的发育。在叶脉发育方面,PIN1能否正确的定位会影响叶脉发育;AS1和AS2共同参与叶片远近轴极性的分化;另外AXR6、MP、BDL、CVP因子功能的缺失影响叶脉发育;生长素、PIN1、Aux/IAA、MP、ATHB8构成反馈循环调控子叶叶脉的形成。     

五步蛇蛇毒金属蛋白酶cDNA的克隆和序列分析

抽提五步蛇毒腺总RNA,通过反转录PCR(RT-PCR)扩增出五步蛇毒腺中一种低分子量金属蛋白酶(aculysinl)的cDNA,克隆到pGMT-vector并测定了全序列.推导其编码的蛋白质序列,发现aculysinl是以酶原形式合成的分泌蛋白,酶原包括信号肽、前肽、金属蛋白酶成熟肽和间隔肽4个部分.金属蛋白酶成熟肽与其它蛇毒金属蛋白酶相比,蛋白质一级结构具有一定的同源性,有一个保守的Zn2+结合位点:HEXXHXXGXXH.Aculysinl含有6个半胱氨酸,推测形成3对链内二硫键.五步蛇低分子量金属蛋白酶cDNA的克隆,为研究蛇毒金属蛋白酶结构与功能的关系,以及开发治疗血栓药物打下了良好的基础     

Populus cathayana males are less affected than females by excess manganese: Comparative proteomic and physiological analyses

The comprehension of sexually different responses in dioecious plants to excess manganese (Mn) stress requires molecular explanation. Physiological and proteomic changes in leaves of Populus cathayana males and females were analyzed after 4 wk of exposure to Mn stress. Under excess Mn conditions, shoot height and photosynthesis decreased more in females than in males. Females also showed severe browning and subcellular damage, higher Mn²⁺ absorption, and different antioxidant enzyme activities compared with males. There were ten differently regulated protein spots induced by excess Mn stress. They were mainly related to photosynthesis, ROS cleaning, and cell signaling associated to ROS, plant cell death, heat shock, cell defense and rescue, and gene expression and regulation. Variation in protein expression between the sexes clearly showed that males have evolved more efficient photosynthesis capacity, more stable gene expression and regulation, and better cell defense and rescue to prevent further injury under excess Mn stress.